Flexible display device

ABSTRACT

In a flexible display device including a non-bending area and a bending area, the flexible display device may include a circuit structure, a display structure on the circuit structure, and an organic layer under or over the circuit structure, the organic layer including a groove corresponding to the bending area.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2019-0035281, filed on Mar. 27, 2019 in the KoreanIntellectual Property Office (KIPO), the entire disclosure of which isincorporated by reference herein.

BACKGROUND 1. Field

Aspects of embodiments of the present disclosure relate to a displaydevice.

2. Description of the Related Art

A conventional display device has been replaced by a thin portabledisplay device. Recently, applications of a flexible display device thatis bendable, rollable, or foldable when in use or during manufacturehave been expanding.

SUMMARY

According to an aspect of embodiments of the present disclosure, aflexible display device having improved bending properties is provided.

According to an aspect of one or more embodiments, a flexible displaydevice including a non-bending area and a bending area may include acircuit structure, a display structure on the circuit structure, and anorganic layer under or over the circuit structure, the organic layerincluding a groove corresponding to the bending area.

In an embodiment, the flexible display device may further include aplanarization layer between the circuit structure and the displaystructure. The display structure may include a first electrode on theplanarization layer, a pixel defining layer at a periphery of the firstelectrode on the planarization layer, an emission layer on the firstelectrode, and a second electrode on the emission layer. The organiclayer may include the planarization layer or the pixel defining layer.

In an embodiment, the flexible display device may further include anencapsulation structure on the display structure. A portion of theencapsulation structure may be inside the groove.

In an embodiment, the encapsulation structure may include a firstinorganic encapsulation layer on the display structure, an organicencapsulation layer on the first inorganic encapsulation layer, and asecond inorganic encapsulation layer on the organic encapsulation layer.A height of a first portion of the second inorganic encapsulation layerinside the groove may be lower than a height of a second portion of thesecond inorganic encapsulation layer outside the groove.

In an embodiment, the groove may be exposed.

In an embodiment, the flexible display device may further include a basestructure under the circuit structure. The base structure may include afirst base layer, a first barrier layer on the first base layer, asecond base layer on the first barrier layer, and a second barrier layerbetween the second base layer and the circuit structure. The organiclayer may include the second base layer.

In an embodiment, the flexible display device may further include anorganic material in the groove.

In an embodiment, the non-bending area may include a first display areaand a second display area located at a side of the first display area,and the bending area may be adjacent to a boundary between the firstdisplay area and the second display area.

In an embodiment, the non-bending area may include a display area and anon-display area located at a side of the display area, and the bendingarea may be adjacent to a boundary between the display area and thenon-display area.

In an embodiment, the organic layer may include a plurality of groovesin the bending area.

According to an aspect of one or more embodiments, a flexible displaydevice including a non-bending area and a bending area may include abase structure, a circuit structure on the base structure, aplanarization layer on the circuit structure, a first electrode on theplanarization layer, a pixel defining layer at a periphery of the firstelectrode on the planarization layer, an emission layer on the firstelectrode, and a second electrode on the emission layer. At least thepixel defining layer may include a groove corresponding to the bendingarea.

In an embodiment, the groove may be defined in the planarization layerand the pixel defining layer.

In an embodiment, the flexible display device may further include anencapsulation structure on the second electrode. A portion of theencapsulation structure may be inside the groove.

In an embodiment, the encapsulation structure may include a firstinorganic encapsulation layer on the second electrode, an organicencapsulation layer on the first inorganic encapsulation layer, and asecond inorganic encapsulation layer on the organic encapsulation layer.A height of a first portion of the second inorganic encapsulation layerinside the groove may be lower than a height of a second portion of thesecond inorganic encapsulation layer outside the groove.

In an embodiment, the groove may be exposed.

According to an aspect of one or more embodiments, a flexible displaydevice including a non-bending area and a bending area may include abase structure including at least one base layer, a circuit structure onthe base structure, a planarization layer on the circuit structure, anda display structure on the planarization layer. The at least one baselayer of the base structure may include a groove corresponding to thebending area.

In an embodiment, the base structure may include a first base layer ofthe at least one base layer, a first barrier layer on the first baselayer, a second base layer of the at least one base layer on the firstbarrier layer, and a second barrier layer between the second base layerand the circuit structure. The groove may be defined in the second baselayer and the second barrier layer.

In an embodiment, the groove may be filled with an organic material.

In an embodiment, the base structure may include a first base layer ofthe at least one base layer, a first barrier layer on the first baselayer, a second base layer of the at least one base layer on the firstbarrier layer, and a second barrier layer between the second base layerand the circuit structure. The groove may be defined in the first baselayer, the first barrier layer, the second base layer, and the secondbarrier layer.

In an embodiment, the circuit structure may include a first inorganicinsulation layer on the base structure and a second inorganic insulationlayer on the first inorganic insulation layer. The first inorganicinsulation layer and the second inorganic insulation layer may cover thegroove, and an organic material may fill the groove on the secondinorganic insulation layer.

In the flexible display device according to embodiments, the groovecorresponding to the bending area may be formed. Therefore, stressapplied to the bending area due to bending may be decreased, and aflexible display device in which the bending area may be bent with arelatively low curvature may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be more clearly understood from the following detaileddescription of some illustrative, non-limiting embodiments taken inconjunction with the accompanying drawings.

FIG. 1 is a plan view illustrating a flexible display device beforebending, according to an embodiment.

FIG. 2 is a cross-sectional view illustrating the flexible displaydevice before and after bending, taken along the line II-II′ in FIG. 1.

FIG. 3 is a cross-sectional view illustrating the flexible displaydevice before and after bending, taken along the line III-III′ in FIG.1.

FIG. 4 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment.

FIG. 5 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment.

FIG. 6 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment.

FIG. 7 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment.

FIG. 8 is a plan view illustrating a region VIII in FIG. 1.

FIG. 9 is a plan view illustrating a region IX in FIG. 1.

DETAILED DESCRIPTION

Herein, flexible display devices in accordance with embodiments will beexplained in further detail with reference to the accompanying drawings.Reference will be made in further detail to some embodiments, examplesof which are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout. In this regard,the present embodiments may have different forms and should not beconstrued as being limited to the descriptions set forth herein.Accordingly, the embodiments are merely described below, by referring tothe figures, to explain aspects of the present description. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items. Expressions such as “at least oneof,” when preceding a list of elements, modify the entire list ofelements and do not modify the individual elements of the list.

It is to be understood that although terms such as “first” and “second”may be used herein to describe various components, these components arenot limited by these terms, and the terms are used to distinguish onecomponent from another.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It is to be further understood that the terms “comprises” and/or“comprising” used herein specify the presence of stated features orcomponents, but do not preclude the presence or addition of one or moreother features or components.

It is to be understood that when a layer, area, or component is referredto as being “formed on” another layer, area, or component, it may bedirectly or indirectly formed on the other layer, area, or component.That is, for example, one or more intervening layers, areas, orcomponents may be present.

Sizes of components in the drawings may be exaggerated for convenienceof explanation. In other words, since sizes and thicknesses ofcomponents in the drawings may be arbitrarily illustrated forconvenience of explanation, the following embodiments are not limitedthereto.

When an embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order.

In embodiments set forth herein, when a layer, area, or component isconnected to another layer, area, or component, the layers, areas, orcomponents may be directly connected to each other, and the layers,areas, or components may also be indirectly connected to each other withanother layer, area, or component therebetween.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments of theinventive concept belong. It is to be further understood that terms,such as those defined in commonly-used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

FIG. 1 is a plan view illustrating a flexible display device beforebending according to an embodiment; FIG. 2 is a cross-sectional viewillustrating the flexible display device before and after bending, takenalong the line II-II′ in FIG. 1; and FIG. 3 is a cross-sectional viewillustrating the flexible display device before and after bending, takenalong the line III-III′ in FIG. 1.

Referring to FIGS. 1, 2, and 3, a flexible display device according toan embodiment may include a non-bending area NBA and a bending area BA.The non-bending area NBA may be a flat area which is not bendable, andthe bending area BA may be a bendable area that is bendable along abending axis during a manufacturing process or during use. A flexibilityof the bending area BA may be greater than a flexibility of thenon-bending area NBA. In an embodiment, the flexible display device mayinclude at least one non-bending area NBA and at least one bending areaBA.

The flexible display device may include a display area DA and anon-display area NDA. Pixels may be disposed in the display area DA, andthe display area DA may display an image through the pixels PX. Padsconnected to external devices and wirings connecting the pads to thepixels may be disposed in the non-display area NDA, and signals fordisplaying an image may be provided to the pixels through the pads andthe wirings.

The display area DA may include a first display area DA1 and a seconddisplay area DA2. The second display area DA2 may be located at at leastone side of the first display area DA1. In an embodiment, the displayarea DA may include four second display areas DA2 respectively locatedat four sides of the first display area DA1. For example, two seconddisplay areas DA2 may be located in a first direction D1 and a seconddirection D2 opposite to the first direction D1, respectively, from thefirst display area DA1, and another two second display areas DA2 may belocated in a third direction D3 crossing the first and second directionsD1 and D2 and a fourth direction D4 opposite to the third direction D3,respectively, from the first display area DA1. In other words, foursecond display areas DA2 may be located at a left side, a right side, anupper side, and a lower side of the first display area DA1,respectively.

The non-display area NDA may be located at a side of the display areaDA. In an embodiment, the non-display area NDA may be located at oneside of the second display area DA2. The first display area DA1 and thenon-display area NDA may be spaced apart from each other with the seconddisplay area DA2 disposed therebetween. For example, the non-displayarea NDA may be located in the fourth direction D4 from the seconddisplay area DA2 that is located in the fourth direction D4 from thefirst display area DA1.

In an embodiment, the non-bending area NBA may include the first displayarea DA1, the second display area DA2, and the non-display area NDA. Inother words, a portion of the non-bending area NBA may be the firstdisplay area DA1 and the second display area DA2 thereby displaying animage, and another portion of the non-bending area NBA may be thenon-display area NDA not displaying an image.

The bending area BA may include a first bending area BA1 and a secondbending area BA2. The first bending area BA1 may be adjacent to aboundary between the first display area DA1 and the second display areaDA2. For example, the first bending area BA1 may be located inside thesecond display area DA2, and may be adjacent to the boundary between thefirst display area DA1 and the second display area DA2. In anembodiment, the bending area BA may include four first bending areas BA1respectively located at boundaries between the four sides of the firstdisplay area DA1 and the second display areas DA2. For example, twofirst bending areas BA1 may be respectively located at boundariesbetween the first display area DA1 and the second display areas DA2located in the first direction D1 or the second direction D2 from thefirst display area DA1, and another two first bending areas BA1 may berespectively located at boundaries between the first display area DA1and the second display areas DA2 located in the third direction D3 orthe fourth direction D4 from the first display area DA1.

The first bending area BA1 may be bent along a bending axis in parallelwith the first direction D1 or the third direction D3. For example, thefirst bending area BA1 located in the first direction D1 or the seconddirection D2 from the first display area DA1 may be bent along a bendingaxis in parallel with the third direction D3, and the first bending areaBA1 located in the third direction D3 or the fourth direction D4 fromthe first display area DA1 may be bent along a bending axis in parallelwith the first direction D1. Accordingly, the first display area DA1 maydisplay an image to a front surface of the flexible display device, andthe second display area DA2 may display an image to a side surface ofthe flexible display device.

The second bending area BA2 may be adjacent to a boundary between thedisplay area DA and the non-display area NDA. In an embodiment, thesecond bending area BA2 may be adjacent to a boundary between the seconddisplay area DA2 and the non-display area NDA. For example, the secondbending area BA2 may be located inside the non-display area NDA, and maybe adjacent to the boundary between the second display area DA2 and thenon-display area NDA. For example, the second bending area BA2 may beadjacent to a boundary between the second display area DA2 located inthe fourth direction D4 from the first display area DA1 and thenon-display area NDA.

The second bending area BA2 may be bent along a bending axis in parallelwith the first direction D1 or the third direction D3. For example, thesecond bending area BA2 located in the fourth direction D4 from thesecond display area DA2 may be bent along a bending axis in parallelwith the first direction D1. Accordingly, the non-bending area NBA ofthe non-display area NDA may face the first display area DA1.

FIG. 4 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment. FIG. 4 may illustrate an example of theflexible display device taken along a line IV-IV′ and a line V-V′ inFIG. 1.

Referring to FIGS. 1 and 4, a flexible display device according to anembodiment may include a base structure 100, a circuit structure 200, aplanarization layer 300, a display structure 400, and an encapsulationstructure 500. An organic layer 300 and 420 may be disposed over thecircuit structure 200, and the organic layer 300 and 420 may havegrooves GR1 and GR2 corresponding to the bending area BA.

The base structure 100 may provide a space or substrate to structureslocated on the base structure 100 thereby supporting elements of theflexible display device. The base structure 100 may include at least onebase layer and at least one barrier layer. In an embodiment, the basestructure 100 may include a first base layer 110, a first barrier layer120, a second base layer 130, and a second barrier layer 140.

The first base layer 110 may include a material having flexibility andan electrical insulating property. For example, the first base layer 110may be formed of an organic material, such as polyimide (PI),polyethylene naphthalate (PEN), polyethylene terephthalate (PET),polyarylate (PAR), polycarbonate (PC), polyetherimide (PEI),polyethersulfone (PS), or the like. However, a material of the firstbase layer 110 is not limited thereto, and any material havingflexibility and an electrical insulating property may be used as thematerial of the first base layer 110.

The first barrier layer 120 may be disposed on the first base layer 110.The first barrier layer 120 may be formed of an inorganic material. Forexample, the first barrier layer 120 may include a material containingsilicon, such as amorphous silicon (a-Si), silicon oxide (SiO_(x)),silicon nitride (SiN_(x)), or the like. The first barrier layer 120 maybe formed on the first base layer 110 that is vulnerable to oxygen andmoisture to prevent or substantially prevent the first base layer 110from being damaged, and may prevent or substantially prevent impuritiessuch as oxygen and moisture from being permeated into the flexibledisplay device.

The second base layer 130 may be disposed on the first barrier layer120. The second base layer 130 may include a material having flexibilityand electrical insulating property. In an embodiment, the second baselayer 120 may include substantially the same material as that of thefirst base layer 110, or may have substantially the same thickness asthat of the first base layer 110. However, embodiments are not limitedthereto, and the first base layer 110 and the second base layer 130 mayinclude a different material or have different thicknesses.

The second barrier layer 140 may be disposed on the second base layer130. The second barrier layer 140 may be formed of an inorganicmaterial. In an embodiment, the second barrier layer 140 may includesubstantially a same material as that of the first barrier layer 120, ormay have substantially the same thickness as that of the first barrierlayer 120. However, embodiments are not limited thereto, and the firstbarrier layer 120 and the second barrier layer 140 may include differentmaterial or have different thicknesses. The second barrier layer 140 maybe formed on the second base layer 130 that is vulnerable to oxygen andmoisture to prevent or substantially prevent the second base layer 130from being damaged, and may prevent or substantially prevent impuritiessuch as oxygen and moisture from being permeated into the flexibledisplay device.

The circuit structure 200 may be disposed on the base structure 100. Thecircuit structure 200 may provide the display structure 400 electricalsignals for driving the display structure 400. The circuit structure 200may include at least one transistor and at least one capacitor. Forexample, the circuit structure 200 may include at least a drivingtransistor T1, a switching transistor T2, and a storage capacitor CST.In an embodiment, the circuit structure 200 may include a buffer layer210, semiconductor layers 221 and 222, a first inorganic insulationlayer 230, gate electrodes 241 and 242, a second inorganic insulationlayer 250, a capacitor electrode 260, a third inorganic insulation layer270, source/drain electrodes 281 and 282, and organic insulation layers291 and 292.

The buffer layer 210 may be disposed on the base structure 100. Thebuffer layer 210 may prevent or substantially prevent impurities frombeing permeated through the base structure 100. Further, the bufferlayer 210 may provide a planarized surface over the buffer layer 210.The buffer layer 210 may be formed of an inorganic material, such assilicon oxide (SiO_(x)), silicon nitride (SiN_(x)), or the like. Inanother embodiment, the buffer layer 210 may be omitted.

The semiconductor layers 221 and 222 may be disposed on the buffer layer210. The semiconductor layers 221 and 222 may include a firstsemiconductor layer 221 and a second semiconductor layer 222. The firstsemiconductor layer 221 and the second semiconductor layer 222 may bespaced apart from each other. The semiconductor layers 221 and 222 maybe formed of amorphous silicon, polycrystalline silicon, or the like. Inan embodiment, the semiconductor layers 221 and 222 may be formed of anoxide semiconductor. Each of the first semiconductor layer 221 and thesecond semiconductor layer 222 may include a source region, a drainregion, and a channel region located between the source region and thedrain region.

The first inorganic insulation layer 230 may be disposed on thesemiconductor layers 221 and 222. The first inorganic insulation layer230 may insulate the gate electrodes 241 and 242 from the semiconductorlayers 221 and 222. The first inorganic insulation layer 230 may beformed of an inorganic material, such as silicon oxide (SiO_(x)),silicon nitride (SiN_(x)), or the like.

The gate electrodes 241 and 242 may be disposed on the first inorganicinsulation layer 230. The gate electrodes 241 and 242 may include afirst gate electrode 241 and a second gate electrode 242. The first gateelectrode 241 may overlap the first semiconductor layer 221, and thesecond gate electrode 242 may be spaced apart from the first gateelectrode 241 and overlap the second semiconductor layer 222. The gateelectrodes 241 and 242 may be formed of a metal, such as gold (Au),silver (Ag), copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd),aluminum (Al), molybdenum (Mo), titanium (Ti), or the like. The secondsemiconductor layer 222 and the second gate electrode 242 that isinsulated from the second semiconductor layer 222 by the first inorganicinsulation layer 230 may form the switching transistor T2.

The second inorganic insulation layer 250 may be disposed on the gateelectrodes 241 and 242. The second inorganic insulation layer 250 mayinsulate the capacitor electrode 260 from the first gate electrode 241.The second inorganic insulation layer 250 may be formed of an inorganicmaterial, such as silicon oxide (SiO_(x)), silicon nitride (SiN_(x)), orthe like.

The capacitor electrode 260 may be disposed on the second inorganicinsulation layer 250. The capacitor electrode 260 may overlap the firstgate electrode 241. The capacitor electrode 260 may be formed of ametal, such as Au, Ag, Cu, Ni, Pt, Pd, Al, Mo, Ti, or the like. Thefirst gate electrode 241 and the capacitor electrode 260 that isinsulated from the first gate electrode 241 by the second inorganicinsulation layer 250 may form the storage capacitor CST.

The third inorganic insulation layer 270 may be disposed on thecapacitor electrode 260. The third inorganic insulation layer 270 mayinsulate the source/drain electrodes 281 and 282 from the capacitorelectrode 260. The third inorganic insulation layer 270 may be formed ofan inorganic material, such as silicon oxide (SiO_(x)), silicon nitride(SiN_(x)), or the like.

The source/drain electrodes 281 and 282 may be disposed on the thirdinorganic insulation layer 270. The source/drain electrodes 281 and 282may include a source electrode 281 and a drain electrode 282. The sourceelectrode 281 and the drain electrode 282 may be respectively connectedto the source region and the drain region of the first semiconductorlayer 221. The source/drain electrodes 281 and 282 may be formed of ametal, such as gold (Au), silver (Ag), copper (Cu), nickel (Ni),platinum (Pt), palladium (Pd), aluminum (Al), molybdenum (Mo), titanium(Ti), or the like. The first semiconductor layer 221, the first gateelectrode 241 that is insulated from the first semiconductor layer 221by the first inorganic insulation layer 230, and the source electrode281 and the drain electrode 282 connected to the first semiconductorlayer 221 may form the driving transistor T1.

In an embodiment, portions of the inorganic insulation layers 210, 230,250, and 270 inside the bending area BA of the circuit structure 200 maybe removed, and the organic insulation layers 291 and 292 may be formedon the removed portions of the inorganic insulation layers 210, 230,250, and 270. In an embodiment, a first organic insulation layer 291 maybe formed on a removed portion of the inorganic insulation layers 210,230, 250, and 270 inside the first bending area BA1 of the circuitstructure 200, and a second organic insulation layer 292 may be formedon a removed portion of the inorganic insulation layers 210, 230, 250,and 270 inside the second bending area BA2 of the circuit structure 200.The first organic insulation layer 291 and the second organic insulationlayer 292 may be formed of an organic material, such as apolyimide-based resin, a polyacrylate-based resin, or the like. Aflexibility of the bending area BA of the circuit structure 200including the organic insulation layers 291 and 292 may be greater thana flexibility of the non-bending area NBA of the circuit structure 200including the inorganic insulation layers 210, 230, 250, and 270.

The planarization layer 300 may be disposed on the circuit structure200. The planarization layer 300 may cover the circuit structure 200 toprotect the circuit structure 200, and may provide a planarized surfaceto the display structure 400 located on the planarization layer 300. Theplanarization layer 300 may be formed of an organic material, such as apolyimide-based resin, a polyacrylate-based resin, or the like.

The display structure 400 may be disposed on the planarization layer300. The display structure 400 may display an image based on electricalsignals provided from the circuit structure 200. The display structure400 may include a first electrode 410, a pixel defining layer 420, anemission layer 430, and a second electrode 440.

The first electrode 410 may be disposed on the planarization layer 300.The first electrode 410 may be connected to the source electrode 281 orthe drain electrode 282 of the driving transistor T1. The firstelectrode 410 may be a transparent electrode or a reflective electrode.In an embodiment, the first electrode 410 may include ITO, IZO, ZnO, orIn₂O₃ when being the transparent electrode, and may include a reflectivelayer formed of any of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and amixture thereof and a transparent layer formed of ITO, IZO, ZnO, orIn₂O₃ when being the reflective electrode. In an embodiment, the firstelectrode 410 may have an ITO-Ag-ITO structure.

The pixel defining layer 420 may be disposed at a periphery of the firstelectrode 410 on the planarization layer 300. In an embodiment, thepixel defining layer 420 may cover an edge of the first electrode 410,and may include an opening that exposes a center portion of the firstelectrode 410. The pixel defining layer 420 may be located at aperiphery of the first electrode 410 to define an emission area, and mayspace the second electrode 440 from the first electrode 410 to preventor substantially prevent an arc or the like from occurring between thefirst electrode 410 and the second electrode 440. The pixel defininglayer 420 may be formed of an organic material, such as apolyimide-based resin, a polyacrylate-based resin, or the like.

The emission layer 430 may be disposed on the first electrode 410. In anembodiment, the emission layer 430 may be disposed on a center portionof the first electrode 410 inside the opening of the pixel defininglayer 420. Holes and electrons respectively provided from the firstelectrode 410 and the second electrode 440 may be combined at theemission layer 430 to form excitons, and light may be generated from theemission layer 430 when the excitons are changed from an excited stateto a ground state. In an embodiment, a hole injection layer (HIL) and/ora hole transport layer (HTL) may be disposed between the first electrode410 and the emission layer 430, and an electron transport layer (ETL)and/or an electron injection layer (EIL) may be disposed on the emissionlayer 430.

The second electrode 440 may be disposed on the emission layer 430. Thesecond electrode 440 may be a transparent electrode or a reflectiveelectrode. In an embodiment, the second electrode 440 may include ITO,IZO, ZnO, or In₂O₃ when being the transparent electrode, and may includea reflective layer formed of any of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir,Cr, and a mixture thereof and a transparent layer formed of ITO, IZO,ZnO, or In2O3 when being the reflective electrode. The first electrode410, the emission layer 430, and the second electrode 440 may form anorganic light emitting diode OLED.

The encapsulation structure 500 may be disposed on the display structure400. The encapsulation structure 500 may cover the display structure 400to protect the display structure 400. In an embodiment, theencapsulation structure 500 may be formed in the display area DA, andmay not be formed in the non-display area NDA. The encapsulationstructure 500 may include at least one inorganic encapsulation layer andat least one organic encapsulation layer. In an embodiment, theencapsulation structure 500 may include a first inorganic encapsulationlayer 510, an organic encapsulation layer 520, and a second inorganicencapsulation layer 530.

The first inorganic encapsulation layer 510 may cover the secondelectrode 440. The first inorganic encapsulation layer 510 may be formedalong a profile of a structure disposed thereunder. In an embodiment,the first inorganic encapsulation layer 510 may be formed of siliconoxynitride (SiO_(x)N_(y)). However, embodiments are not limited thereto,and, in another embodiment, the first inorganic encapsulation layer 510may be formed of silicon oxide, silicon nitride, aluminum oxide,titanium oxide, nickel oxide, or the like.

The organic encapsulation layer 520 may be disposed on the firstinorganic encapsulation layer 510. The organic encapsulation layer 520may have a relatively large thickness, and an upper surface of theorganic encapsulation layer 520 may be substantially planarized insidethe display area DA. The organic encapsulation layer 520 may be formedof polyethylene terephthalate, polyethylene naphthalate, polycarbonate,polyimide, polyethylene sulfonate, polyoxymethylene, polyarylate,hexamehyldisiloxane, or the like.

The second inorganic encapsulation layer 530 may be disposed on theorganic encapsulation layer 520 and covering the organic encapsulationlayer 520. The second inorganic encapsulation layer 530 may be formedalong a profile of the upper surface of the organic encapsulation layer520. In an embodiment, the second inorganic encapsulation layer 530 maybe formed of silicon nitride (SiN_(x)). However, embodiments are notlimited thereto, and, in another embodiment, the second inorganicencapsulation layer 530 may be formed of silicon oxide, siliconoxynitride, aluminum oxide, titanium oxide, nickel oxide, or the like.In an embodiment, each of the first inorganic encapsulation layer 510and the second inorganic encapsulation layer 530 may have an areagreater than that of the organic encapsulation layer 520, and the firstinorganic encapsulation layer 510 and the second inorganic encapsulationlayer 530 may be in contact with each other outside the organicencapsulation layer 520. In other words, the organic encapsulation layer520 may not be exposed by the first inorganic encapsulation layer 510and the second inorganic encapsulation layer 530.

In an embodiment, the grooves GR1 and GR2 corresponding to the bendingarea BA may be formed in the planarization layer 300 and the pixeldefining layer 420. In an embodiment, the grooves GR1 and GR2 may passthrough an entirety of a thickness of the pixel defining layer 420 andat least a portion of a thickness of the planarization layer 300 insidethe bending area BA. A first groove GR1 may be formed in the firstbending area BA1, and a second groove GR2 may be formed in the secondbending area BA2. The first groove GR1 may not overlap the firstelectrode 410.

In an embodiment, the grooves GR1 and GR2 passing through the pixeldefining layer 420 and at least a portion of the planarization layer 300may be formed by photolithography, laser drilling, or the like, in thebending area BA of the flexible display device in which the pixeldefining layer 420 is formed, and the second electrode 440 and theencapsulation structure 500 may be formed in the display area DA on thepixel defining layer 420.

In an embodiment, a portion of the second electrode 440 and a portion ofthe encapsulation structure 500 which are disposed on the pixel defininglayer 420 may be located inside the first groove GR1. As illustrated inFIG. 4, the second electrode 440 and the encapsulation structure 500 maysequentially cover the first groove GR1. Accordingly, for example, aportion of the second electrode 440, a portion of the first inorganicencapsulation layer 510, and a portion of the organic encapsulationlayer 520 may be located inside the first groove GR1. However,embodiments are not limited thereto, and, in an embodiment, a portion ofthe second inorganic encapsulation layer 530 may be additionally locatedinside the first groove GR1.

In an embodiment, a height of a portion of the second inorganicencapsulation layer 530 inside the first groove GR1 may be lower than aheight of another portion of the second inorganic encapsulation layer530 outside the first groove GR1. For example, a height of a lowersurface of the second inorganic encapsulation layer 530 inside the firstgroove GR1 from the base structure 100 may be lower than a height of alower surface of the second inorganic encapsulation layer 530 outsidethe first groove GR1 from the base structure 100. The first inorganicencapsulation layer 510 may be formed along a profile of a structuredisposed thereunder; therefore, the first inorganic encapsulation layer510 may be formed along a profile of the first groove GR1 inside thefirst bending area BA1. The organic encapsulation layer 520 may providea substantially planarized upper surface; however, in an embodiment, aheight of an upper surface of the organic encapsulation layer 520 insidethe first groove GR1 may be lower than a height of an upper surface ofthe organic encapsulation layer 520 outside the first groove GR1 due tothe first groove GR1. Accordingly, a height of a portion of the secondinorganic encapsulation layer 530 inside the first groove GR1 which isformed along the upper surface of the organic encapsulation layer 520may be lower than a height of another portion of the second inorganicencapsulation layer 530 outside the first groove GR1.

When a bending area of a flexible display device according to acomparative example of the prior art in which a groove is not formed isbent, cracks may be formed in a second inorganic encapsulation layeraway from a stress neutral plane, or the second inorganic encapsulationlayer may be detached from an organic encapsulation layer. However, whenthe first bending area BA1 of the flexible display device according toembodiments of the present disclosure in which the first groove GR1 isformed is bent, the second inorganic encapsulation layer 530 inside thefirst bending area BA1 may be located at or near the stress neutralplane due to the first groove GR1, therefore, generation of cracks inthe second inorganic encapsulation layer 530 or detachment of the secondinorganic encapsulation layer 530 from the organic encapsulation layer520 may be prevented or substantially prevented. Further, a contact areabetween the second electrode 440 and the first inorganic encapsulationlayer 510 may increase due to the first groove GR1; therefore, theattachment between the display structure 400 and the encapsulationstructure 500 may increase. Further, a flexible display device in whichthe first bending area BA1 is bent with a relatively low curvature maybe formed.

In an embodiment, the second groove GR2 may be exposed. Accordingly, athickness of the organic layer including the planarization layer 300 andthe pixel defining layer 420 inside the second bending area BA2 may beless than a thickness of the organic layer including the planarizationlayer 300 and the pixel defining layer 420 inside the non-bending areaNBA adjacent to the second bending area BA2. When the second bendingarea BA2 of the flexible display device according to the presentembodiment in which the second groove GR2 is formed is bent, a stressapplied to the second bending area BA2 may decrease due to the decreaseof a thickness of the organic layer including the planarization layer300 and the pixel defining layer 420 inside the second bending area BA2.Further, a flexible display device in which the second bending area BA2is bent with a relatively low curvature may be formed.

FIG. 5 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment. FIG. 5 may illustrate an example of theflexible display device taken along the line IV-IV′ and the line V-V′ inFIG. 1.

Referring to FIGS. 1 and 5, a flexible display device according to anembodiment may include a base structure 100, a circuit structure 200, aplanarization layer 300, a display structure 400, and an encapsulationstructure 500. An organic layer 420 may be disposed over the circuitstructure 200, and the organic layer 420 may have grooves GR1 and GR2corresponding to the bending area BA. Descriptions of elements of theflexible display device described with reference to FIG. 5 which aresubstantially the same as or similar to those of the flexible displaydevice described above with reference to FIG. 4 may not be repeated.

In an embodiment, the grooves GR1 and GR2 corresponding to the bendingarea BA may be formed in the pixel defining layer 420. The grooves GR1and GR2 may pass through at least a portion of a thickness of the pixeldefining layer 420 inside the bending area BA. A first groove GR1 may beformed in the first bending area BA1, and a second groove GR2 may beformed in the second bending area BA2. The first groove GR1 may overlapor may not overlap the first electrode 410.

In an embodiment, the grooves GR1 and GR2 passing through at least aportion of the pixel defining layer 420 may be formed byphotolithography, laser drilling, or the like, in the bending area BA ofthe flexible display device in which the pixel defining layer 420 isformed, and the second electrode 440 and the encapsulation structure 500may be formed in the display area DA on the pixel defining layer 420.

In an embodiment, a portion of the second electrode 440 and a portion ofthe encapsulation structure 500 which are disposed on the pixel defininglayer 420 may be located inside the first groove GR1. As illustrated inFIG. 5, a portion of the second electrode 440 and a portion of the firstinorganic encapsulation layer 510 may be located inside the first grooveGR1.

FIG. 6 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment. FIG. 6 may illustrate an example of theflexible display device taken along the line IV-IV′ and the line V-V′ inFIG. 1.

Referring to FIGS. 1 and 6, a flexible display device according to anembodiment may include a base structure 100, a circuit structure 200, aplanarization layer 300, a display structure 400, and an encapsulationstructure 500. A second base layer 130 including an organic material maybe disposed under the circuit structure 200, and the second base layer130 may have grooves GR1 and GR2 corresponding to the bending area BA.Descriptions of elements of the flexible display device described withreference to FIG. 6 which are substantially the same as or similar tothose of the flexible display device described above with reference toFIG. 4 may not be repeated.

In an embodiment, the grooves GR1 and GR2 corresponding to the bendingarea BA may be formed in the second base layer 130 and the secondbarrier layer 140 of the base structure 100. In an embodiment, thegrooves GR1 and GR2 may pass through an entirety of a thickness of theinorganic insulation layers 210, 230, 250, and 270, an entirety of athickness of the second barrier layer 140, and at least a portion of athickness of the second base layer 130 inside the bending area BA. Afirst groove GR1 may be formed in the first bending area BA1, and asecond groove GR2 may be formed in the second bending area BA2. Thefirst groove GR1 may overlap or may not overlap the first electrode 410.

In an embodiment, the grooves GR1 and GR2 may be filled with an organicmaterial. For example, as illustrated in FIG. 6, the organic insulationlayers 291 and 292 may be respectively disposed inside the grooves GR1and GR2 such that the grooves GR1 and GR2 may be filled with an organicmaterial.

In an embodiment, the grooves GR1 and GR2 passing through the inorganicinsulation layers 210, 230, 250, and 270, the second barrier layer 140,and at least a portion of the second base layer 130 may be formed byphotolithography, laser drilling, or the like, in the bending area BA ofthe flexible display device in which the inorganic insulation layers210, 230, 250, and 270 are formed, and the organic insulation layers 291and 292 respectively filling the grooves GR1 and GR2 with an organicmaterial may be formed.

In a flexible display device according to a comparative example of theprior art in which a groove is not formed in a base structure, theflexible display device may include a second barrier layer formed of aninorganic material inside a bending area such that a stress of the basestructure due to bending may increase. However, in the flexible displaydevice according to embodiments of the present embodiment, the groovesGR1 and GR2 may be formed in the second barrier layer 140 and the secondbase layer 130 inside the bending area BA of the base structure 100, andthe grooves GR1 and GR2 may be filled with an organic material, suchthat a stress of the base structure 100 due to bending may be decreased.In an embodiment, the grooves GR1 and GR2 may not be formed in the firstbarrier layer 120 such that the first barrier layer 120 formed ofinorganic material may be located on the first base layer 110 formed ofan organic material. Therefore, permeation of impurities such as oxygenand moisture into the flexible display device through the first baselayer 110 may be prevented or substantially prevented.

FIG. 7 is a cross-sectional view illustrating a flexible display deviceaccording to an embodiment. FIG. 7 may illustrate an example of theflexible display device taken along the line IV-IV′ and the line V-V′ inFIG. 1.

Referring to FIGS. 1 and 7, a flexible display device according to anembodiment may include a base structure 100, a circuit structure 200, aplanarization layer 300, a display structure 400, and an encapsulationstructure 500. First and second base layers 110 and 130 including anorganic layer may be disposed under the circuit structure 200, and thefirst and second base layers 110 and 130 may have grooves GR1 and GR2corresponding to the bending area BA. Descriptions of elements of theflexible display device described with reference to FIG. 7 which aresubstantially the same as or similar to those of the flexible displaydevice described with reference to FIG. 6 may not be repeated.

In an embodiment, the grooves GR1 and GR2 corresponding to the bendingarea BA may be formed in the first base layer 110, the first barrierlayer 120, the second base layer 130, and the second barrier layer 140of the base structure 100. In an embodiment, the grooves GR1 and GR2 maypass through an entirety of a thickness of the buffer layer 210, anentirety of a thickness of the second barrier layer 140, an entirety ofa thickness of the second base layer 130, an entirety of a thickness ofthe first barrier layer 120, and at least a portion of a thickness ofthe first base layer 110 inside the bending area BA. A first groove GR1may be formed in the first bending area BA1, and a second groove GR2 maybe formed in the second bending area BA2. The first groove GR1 mayoverlap or may not overlap the first electrode 410.

In an embodiment, the first inorganic insulation layer 230 and thesecond inorganic insulation layer 250 may cover the grooves GR1 and GR2,and the grooves GR1 and GR2 may be filled with an organic material. Forexample, as illustrated in FIG. 7, the first inorganic insulation layer230 and the second inorganic insulation layer 250 may sequentially coverthe grooves GR1 and GR2, and the organic insulation layers 291 and 292may be disposed on the second inorganic insulation layer 250 such thatthe grooves GR1 and GR2 respectively covered by the first inorganicinsulation layer 230 and the second inorganic insulation layer 250 maybe filled with an organic material. Further, the third inorganicinsulation layer 270 may cover the organic insulation layers 291 and292.

In an embodiment, the grooves GR1 and GR2 passing through the bufferlayer 210, the second barrier layer 140, the second base layer 130, thefirst barrier layer 120, and at least a portion of the first base layer110 may be formed by photolithography, laser drilling, or the like, inthe bending area BA of the flexible display device in which the bufferlayer 210 is formed, and the first inorganic insulation layer 230 andthe second inorganic insulation layer 250 may be sequentially formed onthe buffer layer 210. Then, the organic insulation layers 291 and 292respectively filling the grooves GR1 and GR2 on the second inorganicinsulation layer 250 with an organic material may be formed, and thethird inorganic insulation layer 270 covering the organic insulationlayers 291 and 292 may be formed on the second inorganic insulationlayer 250.

In a flexible display device according to a comparative example of theprior art in which a groove is not formed in a base structure, theflexible display device may include a first barrier layer and a secondbarrier layer formed of an inorganic material inside a bending area suchthat a stress of the base structure due to bending may increase.However, in the flexible display device according to the presentembodiment, the grooves GR1 and GR2 may be formed in the second barrierlayer 140, the second base layer 130, the first barrier layer 120, andthe first base layer 110 inside the bending area BA of the basestructure 100, and the grooves GR1 and GR2 may be filled with an organicmaterial, such that a stress of the base structure 100 due to bendingmay be decreased. Further, although the grooves GR1 and GR2 are formedin the first barrier layer 120 and the second barrier layer 140, thefirst inorganic insulation layer 230 and the second inorganic insulationlayer 250 formed of an inorganic material may be located on the firstbase layer 110 formed of an organic material. Therefore, permeation ofimpurities such as oxygen and moisture into the flexible display devicethrough the first base layer 110 may be prevented or substantiallyprevented.

FIG. 8 is a plan view illustrating a region VIII in FIG. 1; and FIG. 9is a plan view illustrating a region IX in FIG. 1.

Referring to FIGS. 1, 8, and 9, in an embodiment, a plurality of groovesGR1 and GR2 may be formed inside the bending area BA. For example, aplurality of first grooves GR1 may be formed in the first bending areaBA1, and a plurality of second grooves GR2 may be formed in the secondbending area BA2.

The grooves GR1 and GR2 may have any of various planar shapes, such as aline shape, a dot shape, etc. In an embodiment, the first groove GR1located in the first bending area BA1 may have a dot shape, and thesecond groove GR2 located in the second bending area BA2 may have a lineshape. For example, the first grooves GR1 having the dot shapes may bearranged along the first direction D1 and the third direction D3, andthe second grooves GR2 having the line shapes may be extended in thefirst direction D1 and arranged along the third direction D3. However,embodiments are not limited thereto, and, in another embodiment, thefirst groove GR1 may have another shape, such as a line shape, etc., andthe second groove GR2 may have another shape, such as a dot shape, etc.

The grooves GR1 and GR2 may be substantially uniformly arranged orunevenly arranged inside the bending area BA. The grooves GR1 and GR2are shown substantially uniformly arranged inside the bending area BA inFIGS. 8 and 9; however, the grooves GR1 and GR2 may be unevenly arrangedinside the bending area BA. In an embodiment, for example, the groovesGR1 and GR2 may be relatively densely disposed in a stressed portion inthe bending area BA, and the grooves GR1 and GR2 may be relativelysparsely disposed in a less-stressed portion in the bending area BA. Inother words, the number of the grooves GR1 and GR2 per a unit area maybe relatively large in the stressed portion in the bending area BA, andthe number of the grooves GR1 and GR2 per the unit area may berelatively small in the less-stressed portion in the bending area BA.

In embodiments, the flexible display device according to embodiments maybe applied to a display device included in a computer, a notebook, amobile phone, a smartphone, a smart pad, a PMP, a PDA, an MP3 player, orthe like.

Although the flexible display device according to some embodiments hasbeen described with reference to the drawings, the illustratedembodiments are examples, and may be modified or changed by a personhaving ordinary skill or knowledge in the relevant technical fieldwithout departing from the technical spirit and scope set forth in thefollowing claims.

What is claimed is:
 1. A flexible display device including a non-bendingarea and a bending area, the flexible display device comprising: acircuit structure; a display structure on the circuit structure; and anorganic layer under or over the circuit structure, the organic layercomprising a groove corresponding to the bending area.
 2. The flexibledisplay device of claim 1, further comprising a planarization layerbetween the circuit structure and the display structure, wherein thedisplay structure comprises: a first electrode on the planarizationlayer; a pixel defining layer at a periphery of the first electrode onthe planarization layer; an emission layer on the first electrode; and asecond electrode on the emission layer, and wherein the organic layercomprises the planarization layer or the pixel defining layer.
 3. Theflexible display device of claim 2, further comprising an encapsulationstructure on the display structure, wherein a portion of theencapsulation structure is inside the groove.
 4. The flexible displaydevice of claim 3, wherein the encapsulation structure comprises: afirst inorganic encapsulation layer on the display structure; an organicencapsulation layer on the first inorganic encapsulation layer; and asecond inorganic encapsulation layer on the organic encapsulation layer,and wherein a height of a first portion of the second inorganicencapsulation layer inside the groove is lower than a height of a secondportion of the second inorganic encapsulation layer outside the groove.5. The flexible display device of claim 2, wherein the groove isexposed.
 6. The flexible display device of claim 1, further comprising abase structure under the circuit structure, wherein the base structurecomprises: a first base layer; a first barrier layer on the first baselayer; a second base layer on the first barrier layer; and a secondbarrier layer between the second base layer and the circuit structure,and wherein the organic layer comprises the second base layer.
 7. Theflexible display device of claim 6, further comprising an organicmaterial in the groove.
 8. The flexible display device of claim 1,wherein the non-bending area comprises a first display area and a seconddisplay area located at a side of the first display area, and whereinthe bending area is adjacent to a boundary between the first displayarea and the second display area.
 9. The flexible display device ofclaim 1, wherein the non-bending area comprises a display area and anon-display area located at a side of the display area, and wherein thebending area is adjacent to a boundary between the display area and thenon-display area.
 10. The flexible display device of claim 1, whereinthe organic layer comprises a plurality of grooves in the bending area.11. A flexible display device including a non-bending area and a bendingarea, the flexible display device comprising: a base structure; acircuit structure on the base structure; a planarization layer on thecircuit structure; a first electrode on the planarization layer; a pixeldefining layer at a periphery of the first electrode on theplanarization layer; an emission layer on the first electrode; and asecond electrode on the emission layer, wherein at least the pixeldefining layer comprises a groove corresponding to the bending area. 12.The flexible display device of claim 11, wherein the groove is definedin the planarization layer and the pixel defining layer.
 13. Theflexible display device of claim 11, further comprising an encapsulationstructure on the second electrode, wherein a portion of theencapsulation structure is inside the groove.
 14. The flexible displaydevice of claim 13, wherein the encapsulation structure includes: afirst inorganic encapsulation layer on the second electrode; an organicencapsulation layer on the first inorganic encapsulation layer; and asecond inorganic encapsulation layer on the organic encapsulation layer,and wherein a height of a first portion of the second inorganicencapsulation layer inside the groove is lower than a height of a secondportion of the second inorganic encapsulation layer outside the groove.15. The flexible display device of claim 11, wherein the groove isexposed.
 16. A flexible display device including a non-bending area anda bending area, the flexible display device comprising: a base structurecomprising at least one base layer; a circuit structure on the basestructure; a planarization layer on the circuit structure; and a displaystructure on the planarization layer; wherein the at least one baselayer of the base structure comprises a groove corresponding to thebending area.
 17. The flexible display device of claim 16, wherein thebase structure comprises: a first base layer of the at least one baselayer; a first barrier layer on the first base layer; a second baselayer of the at least one base layer, the second base layer being on thefirst barrier layer; and a second barrier layer between the second baselayer and the circuit structure, and wherein the groove is defined inthe second base layer and the second barrier layer.
 18. The flexibledisplay device of claim 17, wherein the groove is filled with an organicmaterial.
 19. The flexible display device of claim 16, wherein the basestructure comprises: a first base layer of the at least one base layer;a first barrier layer on the first base layer; a second base layer ofthe at least one base layer, the second base layer being on the firstbarrier layer; and a second barrier layer between the second base layerand the circuit structure, and wherein the groove is defined in thefirst base layer, the first barrier layer, the second base layer, andthe second barrier layer.
 20. The flexible display device of claim 19,wherein the circuit structure comprises: a first inorganic insulationlayer on the base structure; and a second inorganic insulation layer onthe first inorganic insulation layer, wherein the first inorganicinsulation layer and the second inorganic insulation layer cover thegroove, and wherein an organic material fills the groove on the secondinorganic insulation layer.